Years ago, Lieutenant Uhura befriended a diplomat from Eeiauo, a land of graceful, catlike beings. The two women exchanged forbidden songs and promised never to reveal their secret.

Now the Starship Enterprise™ must race to save the Eeiauoans before a deadly plague destroys them all. Uhura's secret songs may hold the key to a cure, but the clues are veiled in layers of mystery. The plague is killing humans, threatening other planets -- and Kirk must crack the code before the Enterprise succumbs!